1. Field of the Invention
The present invention relates to a compensation apparatus for compensating a main rotor torque by generating a torque opposing the main rotor torque of a helicopter.
2. Description of Related Art
In a helicopter having a main rotor and a tail rotor, rotation of the main rotor causes the helicopter fuselage to counter with a torque T1 in a direction opposite to the rotational direction of the main rotor. A thrust of the tail rotor is utilized for offsetting the torque T1, and the tail rotor generates a torque T2 in the direction opposite that of torque T1. Further, a vertical tail which is attached to the fuselage with a constant angle of attack generates a torque T3 in the direction identical to that of torque T2. These torques cancel out each other according to the equation T1+T2+T3=0, so as to maintain the attitude of the fuselage.
In recent years, there has been an increasing demand for helicopters which can take off and land on a heliport in urban areas, and the resulting increase in noise must be reduced.
One of the effective countermeasures against the noise is to decrease the rotational speed of the main rotor. However, when the rotational speed of the main rotor changes, the main rotor torque of the helicopter changes and torque T1 no longer balances out torques T2 and T3. In this case, the pilot steers a rudder pedal to change the pitch angle of the tail rotor and adjusts torque T2 to maintain the attitude of the fuselage.
However, when torque T2 is adjusted by steering the rudder pedal, the pilot has to continuously control the rudder pedal, which imposes a great burden on the pilot. In existing helicopters, the pilot steers the rudder pedal to compensate for the change of the main rotor torque T1 by adjusting torque T2 in the direction opposite to that caused by the tail rotor.